package com.sy.simpleegg.serialport.util;

/**
 * Created by admin on 2017/8/23.
 */

public class CRC16 {


    /* 计算CRC16校验码
      *
      * @param bytes 字节数组
      * @return {@link String} 校验码
      * @since 1.0*/
     public static byte[] crc16Checkout(byte[] bytes) {
         int CRC = 0x0000ffff;
         int POLYNOMIAL = 0x0000a001;
         int i, j;
         for (i = 0; i < bytes.length; i++) {
                 CRC ^= ((int) bytes[i] & 0x000000ff);
                 for (j = 0; j < 8; j++) {
                         if ((CRC & 0x00000001) != 0) {
                                 CRC >>= 1;
                                 CRC ^= POLYNOMIAL;
                             } else {
                                 CRC >>= 1;
                             }
                     }
             }
//         return Integer.toHexString(CRC);
         //int类型转成16进制的byte数组
         String byteArrToHex = MyFunc.ByteArrToHexNoSpace(intToBytes(CRC));
         String crcStr = byteArrToHex.substring(4);

         String substring = crcStr.substring(2);
//         Timber.e("substring:"+substring);
         byte[] bytes1 = MyFunc.HexToByteArr(substring);
         String substring2 = crcStr.substring(0,2);
//         Timber.e("substring2:"+substring2);
         byte[] bytes2 = MyFunc.HexToByteArr(substring2);
         byte[] bytes3 = new byte[2];
         System.arraycopy(bytes1,0,bytes3,0,bytes1.length);
         System.arraycopy(bytes2,0,bytes3,1,bytes2.length);
         return bytes3;
    }

    /* int -> byte[] */
    private static byte[] intToBytes(int num) {
        byte[] b = new byte[4];
        for (int i = 0; i < 4; i++) {
            b[i] = (byte) (num >>> (24 - i * 8));
        }

        return b;
    }

    //计算CRC校验码
//    public static byte[]  crc16Checkout(byte[] bytes){
//        int[] table = {
//                0x0000, 0xC0C1, 0xC181, 0x0140, 0xC301, 0x03C0, 0x0280, 0xC241,
//                0xC601, 0x06C0, 0x0780, 0xC741, 0x0500, 0xC5C1, 0xC481, 0x0440,
//                0xCC01, 0x0CC0, 0x0D80, 0xCD41, 0x0F00, 0xCFC1, 0xCE81, 0x0E40,
//                0x0A00, 0xCAC1, 0xCB81, 0x0B40, 0xC901, 0x09C0, 0x0880, 0xC841,
//                0xD801, 0x18C0, 0x1980, 0xD941, 0x1B00, 0xDBC1, 0xDA81, 0x1A40,
//                0x1E00, 0xDEC1, 0xDF81, 0x1F40, 0xDD01, 0x1DC0, 0x1C80, 0xDC41,
//                0x1400, 0xD4C1, 0xD581, 0x1540, 0xD701, 0x17C0, 0x1680, 0xD641,
//                0xD201, 0x12C0, 0x1380, 0xD341, 0x1100, 0xD1C1, 0xD081, 0x1040,
//                0xF001, 0x30C0, 0x3180, 0xF141, 0x3300, 0xF3C1, 0xF281, 0x3240,
//                0x3600, 0xF6C1, 0xF781, 0x3740, 0xF501, 0x35C0, 0x3480, 0xF441,
//                0x3C00, 0xFCC1, 0xFD81, 0x3D40, 0xFF01, 0x3FC0, 0x3E80, 0xFE41,
//                0xFA01, 0x3AC0, 0x3B80, 0xFB41, 0x3900, 0xF9C1, 0xF881, 0x3840,
//                0x2800, 0xE8C1, 0xE981, 0x2940, 0xEB01, 0x2BC0, 0x2A80, 0xEA41,
//                0xEE01, 0x2EC0, 0x2F80, 0xEF41, 0x2D00, 0xEDC1, 0xEC81, 0x2C40,
//                0xE401, 0x24C0, 0x2580, 0xE541, 0x2700, 0xE7C1, 0xE681, 0x2640,
//                0x2200, 0xE2C1, 0xE381, 0x2340, 0xE101, 0x21C0, 0x2080, 0xE041,
//                0xA001, 0x60C0, 0x6180, 0xA141, 0x6300, 0xA3C1, 0xA281, 0x6240,
//                0x6600, 0xA6C1, 0xA781, 0x6740, 0xA501, 0x65C0, 0x6480, 0xA441,
//                0x6C00, 0xACC1, 0xAD81, 0x6D40, 0xAF01, 0x6FC0, 0x6E80, 0xAE41,
//                0xAA01, 0x6AC0, 0x6B80, 0xAB41, 0x6900, 0xA9C1, 0xA881, 0x6840,
//                0x7800, 0xB8C1, 0xB981, 0x7940, 0xBB01, 0x7BC0, 0x7A80, 0xBA41,
//                0xBE01, 0x7EC0, 0x7F80, 0xBF41, 0x7D00, 0xBDC1, 0xBC81, 0x7C40,
//                0xB401, 0x74C0, 0x7580, 0xB541, 0x7700, 0xB7C1, 0xB681, 0x7640,
//                0x7200, 0xB2C1, 0xB381, 0x7340, 0xB101, 0x71C0, 0x7080, 0xB041,
//                0x5000, 0x90C1, 0x9181, 0x5140, 0x9301, 0x53C0, 0x5280, 0x9241,
//                0x9601, 0x56C0, 0x5780, 0x9741, 0x5500, 0x95C1, 0x9481, 0x5440,
//                0x9C01, 0x5CC0, 0x5D80, 0x9D41, 0x5F00, 0x9FC1, 0x9E81, 0x5E40,
//                0x5A00, 0x9AC1, 0x9B81, 0x5B40, 0x9901, 0x59C0, 0x5880, 0x9841,
//                0x8801, 0x48C0, 0x4980, 0x8941, 0x4B00, 0x8BC1, 0x8A81, 0x4A40,
//                0x4E00, 0x8EC1, 0x8F81, 0x4F40, 0x8D01, 0x4DC0, 0x4C80, 0x8C41,
//                0x4400, 0x84C1, 0x8581, 0x4540, 0x8701, 0x47C0, 0x4680, 0x8641,
//                0x8201, 0x42C0, 0x4380, 0x8341, 0x4100, 0x81C1, 0x8081, 0x4040,
//        };
//
//        int crc = 0xffff;
//
//        for (byte b : bytes) {
//            crc = (crc >>> 8) ^ table[(crc ^ b) & 0xff];
//        }
//        String crcStr = Integer.toHexString(crc);
//        String substring = crcStr.substring(2);
//        System.out.println("substring:"+substring);
//        byte[] bytes1 = MyFunc.HexToByteArr(substring);
//        String substring2 = crcStr.substring(0,2);
//        System.out.println("substring2:"+substring2);
//        byte[] bytes2 = MyFunc.HexToByteArr(substring2);
//        byte[] bytes3 = new byte[2];
//        System.arraycopy(bytes1,0,bytes3,0,bytes1.length);
//        System.arraycopy(bytes2,0,bytes3,1,bytes2.length);
//        return bytes3;
//    }

    //判断接收的数据的校验码和计算的校验码是否一致
//    public static boolean verifyCommandCRC(byte[] command) {
//        byte[] sub = new byte[command.length-2];
//        System.arraycopy(command, 0, sub, 0, command.length-2);
////        Timber.e("command的值:"+MyFunc.ByteArrToHex(command)+",长度为:"+command.length);
////        Timber.e("sub的值:"+MyFunc.ByteArrToHex(sub));
//        byte[] paramCRC = crc16Checkout(sub);
////        Timber.e("paramCRC的值:"+MyFunc.ByteArrToHex(paramCRC));
//        boolean flag = (ByteUtil.isByteEqual(paramCRC[0],command[command.length-2])&&
//                ByteUtil.isByteEqual(paramCRC[1],command[command.length-1]));
//        return flag;
//    }

}
